Studies on sewage sludge application on soil properties, nutrient status and yield on pearl millet-wheat cropping system under saline water irrigation
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Date
2019
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CCSHAU, Hisar
Abstract
The present investigation entitled “Studies on sewage sludge application on soil properties, nutrient status and yield of pearl millet-wheat cropping system under saline water irrigation” was conducted at Research Farm of Department of Soil Science, CCS Haryana Agricultural University, Hisar during 2017-18 and 2018-19 with the objective to study the effect of sewage sludge (SS) and saline water irrigation on soil chemical and biological properties, nutrient availability and yield and yield attributes of pearl millet-wheat cropping system. The experimental field was laid out in factorial randomly block design with three irrigation treatments i.e. canal water, 8 and 10 dS/m EC saline water; and five fertilizer treatments i.e. control, SS (5 t/ha), SS (5 t/ha)+50% RDF, SS (5 t/ha)+75% RDF and RDF. The SS was applied only in rabi seasons. On an average, application of saline water irrigation (ECiw 8 and 10 dS/m) caused significant reduction of about 23.6, 31.2 and 24.4, 32.6 per cent of grain yield in pearl millet and wheat, respectively in comparison of canal water. Nutrient uptake was also significantly reduced under saline water irrigation during both years, whereas heavy metal contents in pearl millet and wheat were enhanced with increasing salinity of irrigation water. Na+:K+ and Cl-:SO42- were increased with salinity level while its lower ratio however SS application lowered down these ratios but interaction effects were non-significant. The SS application increased the yield and yield attributes of crops. Among different treatments, RDF achieved significantly higher yield of pearl millet and wheat but statistically at par with SS (5 t/ha)+75% RDF during both the years. Micronutrient and heavy metal contents were significantly increased with sewage sludge application but higher concentrations were recorded with SS (5 t/ha)+75% RDF treatment.
Soil fertility status was altered by application of saline water irrigation. Soil pH was remained unaffected while EC was increase with salinity levels due to accumulation of salts. Soil available nitrogen and phosphorus were significantly reduced with salinity levels while available potassium and sulphur were increased with saline water irrigation might be because addition of K ans S through saline water. Soil organic carbon was also reduced with application of saline water irrigation. Likewise, soil biological properties viz. microbial biomass carbon, dehydrogenase, alkaline phosphatse and urease activities were also significantly reduced with increasing salinity levels at different crop growth stages. DTPA-extractable heavy metals in soil showed trend: Pb > Co > Ni > Cr > Cd. These heavy metals were increased with increasing salinity levels. However, heavy metals were found with in normal range. DTPA-extractable micronutrients (Fe, Mn and Cu) were remained unaffected with saline water irrigation but zinc was significantly reduced. Among various fertilizer treatments, SS (5 t/ha) + 75% RDF significantly increased organic carbon and soil available NPKS. Soil biological properties were significantly enhanced in sewage treated plots as compared to RDF and control at different growth stages of pearl millet and wheat. However, microbial biomass carbon, dehydrogenase, alkaline phosphatse and urease activities were higher at 35 DAS in pearl millet as well as at 75 DAS in wheat followed by harvest and sowing time. Application of sewage sludge increased DTPA-extractable micronutrients and heavy metals in soil and, higher contents were recorded wih SS (5 t/ha) followed by SS (5 t/ha)+50% RDF, SS (5 t/ha)+75% RDF, control and RDF. However, interaction effect of sewage sludge and saline water irrigation was non-significant in our study.